Apparatus for molding and compacting hollow concrete products including pulsating water vibrator means



June 6, 1967 w. G. ABBOTT 3,323,188

APPARATUS FOR MOLDING AND COMPACTING HOLLOW CONCRETE PRODUCTS INCLUDING PULSATING WATER VIBRATOR MEANS Filed Oct. 29, 1964 2 Sheets-Sheet '1 7 22 54 4/ fi Z2 IZ ,52 l/ w I ATTORNEY June 6, 1967 w. G. ABBOTT 3,323,188

APPARATUS FOR MOLDING AND COMPACTING HOLLOW CONCRETE PRODUCTS INCLUDING PULSATING WATER VIBRATOR MEANS Filed Oct. 29, 1964 2 Sheets-$heet 2.

INVENTOR WILLIAM GLEN ABBOTT ATTORNEY United States Patent APPARATUS FOR MOLDING AND COMPACTING HOLLOW CONCRETE PRODUCTS INCLUDING PULSATING WATER VIBRATOR MEANS William Glen Abbott, Washington, D.C., assignor of one-half to Martin Lewis, Jr., Landover, Md. Filed Oct. 29, 1964, Ser. No. 407,482 Claims. (Cl. 25-30) This invention relates to an apparatus for molding and compacting hollow concrete products, and has as its primary object the provision of an improved apparatus for making extremely strong highly compacted hollow concrete products such as pipe or the like.

An additional object of the invention is the provision of a method of this character which employ both high frequency vibration and pulsating hydraulic pressure to effectively compact the concrete during molding thereof.

A further object of the invention resides in the provision of a specialized mold structure including an outer double walled casing and an inner removable core, between which the pipe is molded, and means associated with both the casing and core for imparting high frequency vibration to the concrete during the molding thereof.

A further object of the invention resides in the provision of apparatus wherein the outer .mold casing is double walled, and includes a perforated inner wall and a flexible mold lining, and wherein the inner core has a perforated outer wall with a flexible covering, pulsating water under pressure being introduced into both the double walled outer casing and the inner core, the pulsations thereof being transmitted through the flexible mold liners to the concrete during the molding thereof coincident with the vibrations effected by the vibrators positioned on the external casing and a similar vibrator positioned in the internal core.

Still other objects reside in the combinations of elements, arrangements of parts, and features of construction, as well as in the several and sequential steps of the method.

Still other objects will in part be obvious and in part be pointed out as the description of the invention proceeds and disclosed in the accompanying drawings wherein there is illustrated a preferred form of apparatus for carrying out the method of the instant invention.

In the drawings:

FIGURE 1 is a perspective side view of one form of mold constructed in accordance with the instant invention.

FIGURE 2 is a top plan view thereof with the open position being indicated in dotted lines.

FIGURE 3 is a sectional view taken substantially along the line 33 of FIGURE 2 as viewed in the direction indicated by the arrows.

FIGURE 4 is a sectional view taken substantially along the line 4-4 of FIGURE 3 as viewed in the direction indicated by the arrows, and,

FIGURE 5 is an enlarged fragmentary sectional view of a constructional detail.

Similar reference characters refer to similar parts throughout the several views of the drawings.

Having reference now to the drawings in detail, one form of mold constructed in accordance with the instant invention is generally indicated at and includes a double walled cylindrical outer casing 11 having an outer wall 12 and an inner wall 13, the latter being provided throughout its entire surface with spaced perforations 14. The inner surface of wall 13 is provided with a flexible mold liner 15 which is preferably comprised of an elastomeric plastic. The bottom of the outer casing is closed by a bottom wall 17 of any desired configuration, as shown in FIGURE 3. The casing is mounted on a base ice 18 of any desired resilient material, such as plastic elastomeric polyethylene.

The top of the casing is closed by .a wall 19, and includes an opening 20 in which is seated a rubber sealing bushing 21, see FIGURE 5, through which extends a water inlet pipe 22 having a sealing flange 23 thereon, the inlet pipe extending to a bottom opening 24 near the bottom of the casing. On the opposite side of the outer casing and at the top thereof is an opening 25 which communicates with a water outlet pipe 26 for a purpose to be more fully described hereinafter.

Secured to the exterior wall 12 of the outer mold casing are a plurality of high frequency, high amplitude electric vibrators 27, the vibrators being mounted in metal sleeves 28 which in turn are fixedly secured to the casing as by means of bolts 29 extending through plates 30. The vibrators may be of any desired conventional type, and normally vibrate at a rate of 12,000 to 20,000 vibrations per minute (v.p.m.) and are of sufficient power and amplitude to properly compact the concrete mix in the mold, as will be described hereinafter. Suitable electric current is supplied to the vibrators from any desired external source.

As best shown in FIGURE 2, the outer casing is longitudinally split, and is provided with suitable latches 31-32, by means of which the same may be separated. Also as best shown in FIGURES 1 and 2 the two separate halves of the-mold structure are each provided with inlets 22 and outlets 26. The ends of the mold along the lines of separation are obviously closed by suitable closure plates.

An inner mold core, generally indicated at 35, is also provided and is of generally cylindrical construction including an annular wall 36 provided with a plurality of perforations 37 spaced throughout its entire area. A bottom wall 38 is also provided, as is a top wall 39. The top wall is provided with a rubber bushing 40 similar to the bushing 21 through which extends a water inlet pipe 41 having an opening 42 adjacent the bottom wall 38. A water outlet 41a is also positioned in the top wall for a purpose to be described more fully hereinafter. Depending from the underside of the top wall 39 of the mold core 35 is an inverted cup-shaped member 43 having a conforming cup-shaped pad 43' of suitable resilient material, for example, sponge rubber, suitably affixed therein. The rubber pad 43' engages with the upper end of an elongated vibrator 50, which is of the high cycle type, and may be varied in frequency from low through medium to high, as desired. Current is supplied to the vibrator 50 by means of wires 51 which extend through suitable openings in top wall 39, cup-shaped member 43 and pad 43'. The lower end of vibrator 50 seats on a cup-shaped pad 45, suitably affixed to a second cup-shaped member 45 arranged on and suitably secured to bottom wall 38 of the mold core 35, whereby both the upper and lower ends of the vibrator 50 are engaged by and the vibrator is confined by the cup-shaped members 43 and 45 and is retained substantially concentrically within the core 35. The outer side of wall 36 is provided with a flexible mold liner covering 52, which is preferably comprised of an elastomeric plastic similar to the mold liner 15 previously described. The bottom of the space between the outer casing and the inner core is closed by a removable pallet 55, of any desired configuration, but which is shown in the illustrative embodiment with an offset portion to form a pipe lip for connection to an adjacent section.

In the use and operation of the device, the outer mold casing is closed and locked together by means of the fastenings 3132 around the pallet 55 and then placed in proper alignment on the resilient base plate 18. The inner core is then inserted in the outside mold, in any desired manner, so that its lower end is contained within the opening formed in the center of the pallet 55. Pulsating water is then supplied to the interior of the double walled casing through the inlets 22 and to the inner core through the inlet 41 at a pressure of 5 to 7 pounds per square inch (p.s.i.) and the external vibrators 27 and the internal vibrator 50 are both actuated. The concrete mix is then fed into the mold or the space between the lines and 52 and distributed evenly around the circumference thereof until this space is entirely filled. The top of the mold is then sealed with an annulus 54, which is suitably inset within the upper end of space 53 and clamped therein by means of conventional clamps (not shown) to form a pressure seal engaging with and confining the concrete in the top thereof, and the pressure of the pulsating water is raised to 75 to 100 psi. for a relatively short time in the inside of the mold. The pulsation rate of the water is preferably between 400 and 700 pulses per minute (p.p.rn.) During and throughout these entire operations, the outside vibrators 27 are maintained at constant high frequency, while the inside mold vibrator 50 is varied from low through medium to the maximum frequency. This may be effected in any conventional manner as by mechanically varying the speed of the alternator supplying electric current for the inside vibrator, and by this means a multifrequency range of vibration from low to high and high to low is created which covers the full range of the resonance frequencie of the various size particles in the concrete mix, thus producing a state of optimum density in the concrete mix. After this step the pulsating water pressure is again reduced to 5 to 7 p.s.i. and the outside vibrators are shut down. This pressure is maintained while the inner core is lifted from the mold, the core being slowly rotated during removal. It is to be understood that, as the bottom wall 17 of casing 11 is mounted on the resilient base 18, the entire unit is free for universal movement and substantially floats thereon.

After this procedure the outside mold containing the concrete article is removed to the curing room where the locks 32 are opened and the two parts of the mold carefully separated from around the concrete, the article thus being left standing on its pallet 55, at which time it is ready for steam curing.

From the foregoing, it will now be seen that there is herein provided an improved apparatus for molding and compacting hollow concrete articles which accomplish all of the objects of this invention, and others, including many advantages of great practical utility and commercial importance.

As many embodiments may be made of this inventive concept, and as many modifications may be made in the embodiment hereinbefore shown and described, it is to be understood that all matter herein is to be interpreted merely as illustrative and not in a limiting sense.

What is claimed is:

1. Apparatus for molding and compacting hollow concrete products comprising a separable double walled hollow outer mold casing including a perforated inner wall and a flexible mold liner, high frequency high cycle electric vibrators attached to the exterior of the outer casing, a hollow inner mold core having a perforated metal wall and a flexible external mold liner, a high cycle electric vibrator internally of said inner mold core, and means for introducing pulsating water under pressure into the outer mold casing and the inner mold core.

2. The structure of claim 1 wherein the means for introducing pulsating water under pressure include inlets at the bottom of the mold casing and mold core, and outlets at the top thereof.

3. The structure of claim 1 wherein the flexible mold liners are comprised of elastomeric plastic.

4. The structure of claim 1 wherein the mold casing and core are mounted on a. resilient base.

5. The structure of claim 1 wherein the mold core is removable from the mold casing.

References Cited 7 UNITED STATES PATENTS 1,740,711 12/1929 Pelton 252l 2,614,312 10/1952 Rankin et a1 25-41 2,969,575 1/1961 Gagne 2541 3,107,158 10/1963 Ahlberg 25-41 3,177,554 4/1965 Larkfeldt 25-41 FOREIGN PATENTS 117,739 3/1958 Russia.

I. SPENCER OVERHOLSER, Primary Examiner.

ROBERT D. BALDWIN, ROBERT F. WHITE,

Examiners. 

1. APPARATUS FOR MOLDING AND COMPACTING HOLLOW CONCRETE PRODUCTS COMPRISING A SEPARABLE DOUBLE WALLED HOLLOW OUTER MOLD CASING INCLUDING A PERFORATED INNER WALL AND A FLEXIBLE MOLD LINER, HIGH FREQUENCY HIGH CYCLE ELECTRIC VIBRATORS ATTACHED TO THE EXTERIOR OF THE OUTER CASING, A HOLLOW INNER MOLD CORE HAVING A PERFORATED METAL WALL AND A FLEXIBLE EXTERNAL MOLD LINER, A HIGH CYCLE ELECTRIC VIBRATOR INTERNALLY OF SAID INNER MOLD CORE, AND MEANS FOR INTRODUCING PULSATING WATER UNDER PRESSURE INTO THE OUTER MOLD CASING AND THE INNER MOLD CORE. 